Many well known organic synthesis reactions are conducted in the presence of transition metal complex catalysts such as Ni[P(OMe).sub.3 ].sub.4, that is tetrakis trimethylphosphite nickel (0). Typical examples of the type of reactions which may be catalyzed with such transition metal complexes, include isomerization, hydrogenation, hydrocyanation, olefin metathesis, hydroformylation, hydrosilylation and olefin polymerization. For further details of such types of reactions and the catalysts used, see Transition Metals in Homogeneous Catalysis, (Ed.) Schrauzer, Marcel Rekker, Inc. (1971), particularly pages 14 to 51 and 149-216, which are incorporated herein by reference.
It is known that reactions of the basic types mentioned above are most efficient if the catalyst is in a different phase than the reactants. For example, if the reactants are liquid and the catalyst solid, it is advantageous in that the catalyst can easily be separated from the pure product. Also, recycle of the catalyst is much easier.
Other advantages which flow from use of catalyst systems which are heterogeneous, that is, of a different phase than the reactants, include advantages in clean-up of the system (simple filtering of the catalyst after the reaction) and catalyst economics since recycle is much easier. However, by far the most important advantages of a heterogeneous versus a homogeneous catalyst system, especially in industrial processes, is that soluble products are not contaminated with catalyst material in heterogeneously catalyzed reactions; also, equally as important, heterogeneous catalysts lend themselves much more easily to continuous processes which of course, are most often far more economical than batch processes.
In the past, attempts have been made to heterogenize normally homogeneous organo-metallic catalysts, see, for example, G. Manecke and W. Storck, Angew, Chem. (Eng.) 17 (1978) 657; A. K. Smith and J. M. Basset, J. Molec. Cat., 2 (1977) 229; J. C. Bailar, Catal. Rev. Sci, Eng., 10 (1974) 17; R. H. Grubbs, Strem Chemiker, IV (1976) 3; and C. U. Pittman and G. O. Evans, Chem. Technol., 3 (1973) 560. The most common approach is to anchor the normally used organometallic catalyst on a polymer support system. One such technique is to functionalize polystyrene with --PR.sub.2 groups. The --PR.sub.2 groups act as a complexation site for the metal moiety. However, disadvantages occur with this system of supporting homogeneous catalysts on polymers. Catalytic longevity may be sacrificed and, catalyst recycle is difficult because the catalyst is attached to supporting polymer structures, normally by only one coordination site. In contrast to the previous use of conventional polymer support structures reported in the literature cited herein, the present invention employs a technique of conversion of homogeneous catalysts to heterogeneous analogs by use of polydentate ligands which connect metal moieties, thus securing the metal atom in the polymer matrix by more than one coordination site. The technique has wide versatility. It produces a solid polymer which itself functions as the catalyst without need for any supporting substrate like polystyrene resin; and the polymerized heterogeneous catalyst functions substantially equally with respect to catalytic activity as the "parent" homogeneous catalyst.
Accordingly a primary object of this invention is to provide a technique of converting normally homogeneous transition metal complex catalysts to heterogeneous phase catalysts of substantially equal catalytic activity as the normally homogeneous phase "parent" catalyst.
Another object of this invention is to provide a catalyst conversion technique which is convenient to use, simple, economical, and which allows practice of industrial processes which normally employ homogeneous catalysts, now for the first time in many instances, with heterogeneous catalysts, thus obtaining the benefits which normally flow therefrom, such as significant reduction of catalyst contamination in products, greater ease of conducting continuous processes, easier removal of the catalyst after the reaction is completed, and catalyst recycle.
An even further object of this invention is to prepare heterogeneous catalysts from "parent" normally homogeneous organometallic transition metal complex catalysts with the heterogeneous polymerized catalysts being substantially equal in catalytic activity to the homogeneous "parent" catalyst.
And a still further object is to develop a catalyst conversion method which has general applicability and may be used for converting transition metal complex catalysts of nearly any industrial reaction from same-phase, homogeneous catalyst to different-phase, heterogeneous, polymer catalysts.
The method and manner of accomplishing these as well as other objects will become apparent from the detailed description of the invention, which follows.